Backpack style propulsion units have been arround in northern climates for many years and used by skiers to provide fresh air, exercise, fun, and recreation, during times of the year when people are inclined towards passivity. Previous attempts at providing a propulsion support unit suitable for the interchangability of readily available propelling means have been meager, limited, and unsatisfactory. Heretofore supporting devices have not provided a means for altering thrust angles essential for safe, efficient, navigation and control by the operator, a contoured framework for even distribution of loads and comfort of the operator, a means for folding, collapsing, and disassembling the device for storage or transport, and a means of activating the primer mover from operating position without resorting to unduly heavy electrical starting motors or an assistant to turn an engine over.
Reference patent by H. M. Morrill, U.S. Pat. No. 2,456,440, Dec. 1948: Research and experiment in the art have shown the need to have an efficient weight distribution system with the central mass as close as possible to the back of the operator for good balance, comfort, and control, when using a device of the present invention. With our present technology, the prime movers are generally gas engines weighing 25-30 pounds in a size that would develop effective thrust to move a person. Using a spherical cage and a pulling propeller as shown in Morrill's principal embodiment places the central mass or center of gravity (C.G.) too far aft or rearward to be comfortable and causes strain on the lower back and poor balance. The present invention distributes the weight evenly on the shoulders and hips of the operator and places the C.G. adjacent the back of the person. This is further facilitated by angling the thrust in a downward direction so the reaction force tends to lift the weight of the device, relieving the operator. The spherical cage that Morrill realizes would, in reality, be unduly heavy, bulky, and tiring, simply due to it's size and weight and our present knowledge of light, strong materials. According to Morrill's claims the horizontal (7) support bar which the operator secures to his forearm to support the prime mover would not prevent the inward twisting force as well as the downward force exerted by the weight of the device. Morrill's fuel tank position is dangerous because forward falls are the most common when using this type of device and the tank would be subject to impact damage and leaking and present a fire hazard to the operator. Also in a fall, the supporting arm could not be used to brace oneself, whereas the present invention allows freedom of arms and hands when desired. Finally, horizontal support bar (7) and back rest (31) are substantially rigidly secured to spherical cage (18) thereby limiting any directional control of thrust or navigational control without discomfort to the operator. These defects and others are overcome with the present invention.